System and method to improve USB mass storage device arrival acceleration for redirected USB mass storage devices

ABSTRACT

In certain information handling system environments, physical devices connected to a client are redirected to a server or other information handling system. The time to redirect a universal serial bus (USB) mass storage device may be lengthy given that the same metadata must be read several times. Arrival time of a redirected USB mass storage device may be decreased by collecting the complete metadata at the client and transmitting that complete metadata to the server. The server builds a metadata cache to store the metadata received from the client. Efficiencies are achieved by caching the complete metadata associated with the redirected device at the server instead of making repeated transactions requesting the same metadata from the client.

TECHNICAL FIELD

This disclosure generally relates to improving universal serial bus(USB) mass storage device arrival time for redirected USB mass storagedevices over a network, for example, a wide-area network (WAN).

BACKGROUND

As the value and use of information continues to increase, individualsand businesses seek additional ways to process and store information.One option available to these users is an information handling system orcomputing system. An information handling system generally processes,compiles, stores, and/or communicates information or data for business,personal, or other purposes thereby allowing users to take advantage ofthe value of the information. Because technology and informationhandling needs and requirements vary between different users orapplications, information handling systems may vary with respect to thetype of information handled; the methods for handling the information;the methods for processing, storing or communicating the information;the amount of information processed, stored, or communicated; and thespeed and efficiency with which the information is processed, stored, orcommunicated. The variations in information handling systems allow forinformation handling systems to be general or configured for a specificuser or specific use such as financial transaction processing, airlinereservations, enterprise data storage, or global communications. Inaddition, information handling systems may include or comprise a varietyof hardware and software components that may be configured to process,store, and communicate information and may include one or more computersystems, data storage systems, and networking systems. The softwarecomponents may comprise one or more modules that contain instructionsthat when executed perform one or more functions.

The information handling system may include one or more operatingsystems. An operating system serves many functions, such as controllingaccess to hardware resources and controlling the execution ofapplication software. Operating systems also provide resources andservices to support application software. These resources and servicesmay include a file system, a centralized configuration database (such asthe registry found in Microsoft Windows operating systems), a directoryservice, a graphical user interface, a networking stack, device drivers,and device management software. In some instances, services may beprovided by other application software running on the informationhandling system, such as a database server.

Some information handling systems are designed to interact with otherinformation handling systems over a network connection. In someinstances, the information handling systems may share resources over thenetwork. Certain of the networked information handling systems may actas servers, while others act as clients. In such systems, clientapplications and client devices may be designed so that the majority ofthe heavily used resources are at a shared information handling system,such as a centralized server. The client devices may have minimalmemory, disk storage, and processor power. Use of such client devicesmay reduce the total cost of ownership because of the reduced use ofresources at the client devices and because the clients can be centrallyadministered and updated from the server. Such client devices may beparticularly well-suited for a network which can handle a significantnumber of devices.

Virtual desktop infrastructure (VDI) environments may include any one ormore information handling systems. A virtual environment, such as a VDI,separates a desktop environment and its associated software in a datacenter or server, from the information handling system that is used toaccess the desktop environment. A “virtual desktop” may refer to anynumber of methodologies including server-based computing (SBC) where anumber of users share the desktop of a server-based operating system,VDI where each user gets their own virtual machine which typically runsa client operating system, and application virtualization technologiesthat concentrate more closely on making specific applications availableto users with these applications, for example, being hosted on a remotesystem or streamed to the user's local system. With respect to thevirtual desktop technologies described, SBC is often regarded as beingappropriate for task/call-center type environments, while VDI is morecommonly deployed for knowledge workers who require a higher level ofuser personalization, and application virtualization technologies may becommonly deployed across SBC, VDI and physical desktop environments tosolve business challenges such as legacy application OS compatibility.

Prior universal serial bus (USB) technology utilized in VDI environmentsemulated virtual USB hardware on a virtual USB bus driver on aninformation handling system, such as a server. The operating system ofthe server loaded a real driver and applications for the virtual USBhardware in the same way as such would be loaded for real physicalhardware. When the application tried to access or use a virtual deviceor virtual hardware, the requests from the application would betranslated as transaction requests (for example, URB) directed to thevirtual USB hardware on the server. The virtual USB bus driverredirected the USB request block (URB) transactions to anotherinformation handling system, such as a client, where the real physicalhardware was actually located. The received transaction requests fromthe server were then submitted to the real USB hardware via a stubdriver on the client. The resulting responses from the real USB hardwarewould then be transported back to the server and pumped to the virtualUSB bus driver. The virtual USB bus driver then passed these responsesback to the respective applications via the real driver, thus completingthe loop. These URBs may contain read/write requests to a USB massstorage device.

The arrival time for a redirected USB mass storage device may be verylarge or excessive over a wide-area network (WAN). The transactions,such as URBs, to and the responses from the physical USB mass storagedevice (collectively, “input/output (I/O) transactions”) may be numerousand large. These I/O transactions exchanged between the server and theclient may require several minutes depending on the latency of thenetwork. One reason for such delay is the that the server may be thatthe server (location of the virtual USB mass storage device) attempts toread the same metadata associated with the I/O transactions many times.The reading of this metadata may take multiple I/O transactions as nosingle I/O transaction may request complete metadata. The presentdisclosure provides systems and methods to address this problem.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, in which like referencenumbers indicate like features, and wherein:

FIG. 1 illustrates an example configuration of networked informationhandling systems according to one embodiment of the present disclosure;

FIG. 2 illustrates an example system of a networked client and serveraccording to one embodiment of the present disclosure;

FIG. 3 illustrates an example of steps involved in one method accordingto one embodiment of the present disclosure;

FIG. 4 illustrates an example of steps involved in one method accordingto one embodiment of the present disclosure;

FIG. 5 illustrates an example of steps involved in one method accordingto one embodiment of the present disclosure; and

FIG. 6 illustrates an example computing system according to oneembodiment of the present disclosure.

DESCRIPTION

This disclosure generally relates to remote computing and, inparticular, relates to utilizing read-ahead metadata to increase theefficiency of input/output (I/O) transactions related to a redirecteduniversal serial bus (USB) mass storage device. For example, when a USBmass storage device is redirected, the arrival time may require a verylong time period over certain networks, such as wide-area networks(WAN), due to the exchange of universal request blocks (URB) andresponses between the client and server. In one example, a Kingston USBmass storage device exchanges 2000 I/O transactions between a client anda server when the USB mass storage device is redirected at the server.If the network has a latency of 150 milliseconds, then 2000 I/Otransactions multiplied by the 150 millisecond latency means that it maytake up to five minutes or more for the complete USB mass storage deviceinformation required to create the virtual USB mass storage device atthe server is delivered so that the server can build the necessary filesystem associated with the virtual USB mass storage device. This may bedue to several reasons including, for example, the operating system (OS)of the server attempting to read the same metadata associated with theUSB mass storage device to be virtualized many times. Such metadata mayinclude, for example, information related to the master boot record(MBR), boot sector, and partition table for each partition. The metadatafor a file allocation table (FAT) file system may include FAT area androot directory. The metadata for a new technology file system (NTFS) mayinclude a master file table.

For purposes of this disclosure, an information handling system mayinclude any instrumentality or aggregate of instrumentalities operableto compute, classify, process, transmit, receive, retrieve, originate,switch, store, display, manifest, detect, record, reproduce, handle, orutilize any form of information, intelligence, or data for business,scientific, control, or other purposes. For example, an informationhandling system may be a personal computer, a network storage device, orany other suitable device and may vary in size, shape, performance,functionality, and price. The information handling system may includerandom access memory (RAM), one or more processing resources such as acentral processing unit (CPU) or hardware or software control logic,read-only memory (ROM), and/or other types of nonvolatile memory.Additional components of the information handling system may include oneor more disk drives, one or more network ports for communication withexternal devices as well as various input and output (I/O) devices, suchas a keyboard, a mouse, and a video display. The information handlingsystem may also include one or more buses operable to transmitcommunications between the various hardware components.

For the purposes of this disclosure, computer-readable storage media mayinclude any instrumentality or aggregation of instrumentalities that mayretain data and/or instructions for a period of time. Computer-readablestorage media may include, for example without limitation, storage mediasuch as a direct access storage device (for example, a hard disk driveor floppy disk), a sequential access storage device (for example, a tapedisk drive), compact disk, compact disk read-only memory (CD-ROM),digital video disc (DVD), random access memory (RAM), ROM, electricallyerasable programmable read-only memory (EEPROM), and/or flash memory.

As used herein, a “local” device of a system, or a device “locally”connected to a system, may be a device directly connected to the systemusing one or more wires or connectors (for example, physically connectedto the system), a device indirectly connected to the system using one ormore hubs, or a device directly connected to the system using a wirelesslink. Furthermore, in one aspect of the present disclosure, a localdevice of a system or a device locally connected to a system may includea device within the system (for example, an internal device).

The present disclosure is now described in detail with reference to afew embodiments thereof as illustrated in the accompanying drawings. Inthe following description, numerous specific details are set forth inorder to provide a thorough understanding of the present disclosure.However, the present disclosure may be practiced without some or all ofthese specific details. In other instances, well known process stepsand/or structures have not been described in detail in order not tounnecessarily obscure the present disclosure. In addition, while thedisclosure is described in conjunction with the particular embodiments,it should be understood that this description is not intended to limitthe disclosure to the described embodiments. To the contrary, thedescription is intended to cover alternatives, modifications, andequivalents as may be included within the spirit and scope of thedisclosure as defined by the appended claims.

In systems based on the server/client model, certain resources may beshared amongst clients or between clients and servers via a network. Forexample, in one embodiment the network is a WAN or a LAN. In somecircumstances, it may be advantageous to make peripheral devicesconnected locally at one client device available to one or more otherinformation handling systems on the network.

One type of client information handling system may be a thin client,also known as a lean or slim client. A thin client is a computer orcomputer program which depends on some other computer, for example, aserver, to fulfill at least some of the computational roles required ofthe thin client. In certain configurations of one or more informationhandling systems, multiple user may login to the same server. The usersmay be permitted to work simultaneously even though they may bephysically located at separate locations. According to the presentdisclosure, the users may be permitted to simultaneously access data,applications, and/or hardware associated with the server (or otherinformation handling system). The server itself may be a physicalmachine or a virtual machine (VM).

A user may access devices redirected to the server as if those devicesare available locally to the user by connecting all the necessaryperipherals. For example, the user may connect to USB printers, USBscanners, USB mass storage devices, and any other device known to one ofordinary skill in the art.

According to the present disclosure, individual interfaces associatedwith a single physical device may be installed locally or may beredirected to another information handling device, such as a server.Interfaces forwarded to the server may be mounted as virtual devices atthe server and may be shared with additional information handlingsystems. In some embodiments, one interface associated with a compositedevice may be redirected to one server, a second interface may beredirected to a second server, and a third interface may be installedlocally.

As an example, if a USB mass storage device is connected to a givenclient via a standard USB connection, the locally connected USB massstorage device may be redirected to the server. The redirected USB massstorage device may then be installed locally for use by any number ofclients. The server treats the USB mass storage device as a virtual massstorage device attached to the server.

FIG. 1 at 100 illustrates an example configuration of a networkedinformation handling system. In particular embodiments, one or moreclient devices 120 and one or more servers 140 are connected via network110. Network 110 may be a WAN, local-area network (LAN) or any othertype of network known to one of ordinary skill in the art. Many types ofperipheral devices may be connected locally to the client devices 120.As shown in FIG. 1, in some embodiments, one or more USB devices 130connect to the client devices 120. According to the present disclosure,one or more USB mass storage devices 130 may appear to one or more ofservers 140 as if they are locally installed on and connected to thoseservers 140. In certain embodiments, these USB mass storage devices 130may be redirected such that they appear to be locally installed orlocally shared with another client device 120. In one embodiment, theDell Wyse TCX USB Virtualization is used to virtualize the USB massstorage device 130. In one or more embodiments, one or more USB massstorage devices 130 may be virtualized as virtual USB mass storagedevice 150 at a server 140.

FIG. 2 at 200 illustrates an example embodiment of a system configuredto redirect a USB mass storage device 130, for example, a USB hard diskdrive (HDD). In a particular embodiment, the configuration shown in FIG.2 illustrates a virtual environment that may include one or more ofVirtual Desktop Infrastructure (VDI) environment, Server-Based Computing(SBC) environment, and application virtualization technologies. Thisdisclosure contemplates any number of virtual environments as known toone of ordinary skill in the art. As a result of the suitability ofthese technologies for different user types, many organizations arechoosing to implement a hybrid approach that uses each of thetechnologies including using multiple vendors within each technology.The decision as to which users to allocate to which technology type maybe difficult in advance of any actual implementation of a particulartechnology for a particular user.

In particular embodiments, client 120 connects to server 140 via network110. In one embodiment, network 110 may be a WAN network. In otherembodiments, network 110 may be a LAN network or any other type ofnetwork known to one of ordinary skill in the art. Network 110 may alsobe a high latency network.

When a USB mass storage device 130 is initially connected to client 120,client 120 may attempt to initialize USB mass storage device 130 byattempting to load a USB bus driver 202. According to the presentdisclosure, client 120 may determine (or may permit a user to determine)whether to redirect USB mass storage device 130 upon connection of theUSB mass storage device 130, as part of the initialization of USB massstorage device 130. In particular embodiments, client 120 may make a newdetermination regarding the installation of USB mass storage device 130after USB mass storage device 130 has been initialized. For example, auser may decide that the USB mass storage device 130 that was previouslyinstalled on its local client 120 should be redirected to server 140.Client 120 may be configured to automatically install all or onlycertain USB mass storage devices 130 locally, may be configured toautomatically redirect all or certain USB mass storage devices 130 toserver 140, or may be configured to request input from a user of client120 or from another source to determine whether to install a particularUSB mass storage device 130 locally or to redirect it.

If a USB mass storage device 130 is configured to be redirected toserver 140, the redirection may operate generally as described in U.S.Pat. No. 8,010,630 to Barreto, et al., which is incorporated herein byreference. A proxy client 206 on client 120 may coordinatecommunications between USB mass storage device 130 and an agent 208running on server 140. In particular proxy client 208 may be configuredto receive socket connection information from server 140 and initiateredirecting I/O transactions between USB mass storage device 130 andagent 208. Agent 208 may be configured to register with the OS of server140 to receive notification of an establishment of any remote accessconnection. In one embodiment, proxy client 206 may be configured toreceive socket connection information from agent 208 of server 140 andinitiate redirecting I/O transactions to and from USB mass storagedevice 130 to agent 208 on server 140.

Virtual USB bus driver 214 receives information about USB mass storagedevice 130 that is to be redirected from agent 208. Virtual USB busdriver 214 may be a Wyse virtual USB bus driver wvusbbus.sys, forexample. Virtual USB bus driver 214 calls real driver 212 associatedwith the virtual USB mass storage device 150, to complete theinitialization of the virtual USB mass storage device 150 on server 140.Based on the USB mass storage device type enumerated by the virtual USBbus driver 214, the appropriate OS stack will be created. The I/Otransactions will reach the bottom of the OS stack which is the virtualUSB bus driver 214. The virtual USB bus driver 214 along with anauxiliary server, transfers these I/O transactions to the client 120 viathe agent 208 on the server 140 and the proxy client 206 on the client120.

The virtual USB mass storage device 150 associated with the USB massstorage device 130 then functions as if the USB mass storage device 130was locally connected to server 140 (as indicated by the dashed linebetween USB mass storage device 130 and virtual USB mass storage device150). The virtual USB mass storage device 150 may thus be made availableto application 210 running on server 140, which treats the virtual USBmass storage device 150 as a local device.

Metadata associated with USB mass storage device 130 may be collected atthe proxy client 206. The collection of metadata at the proxy client 206may be referred to as a read-ahead mechanism. The collection of metadatais stored at the proxy client 206. Metadata associated with the USB massstorage device 130 that has been redirected as virtual USB mass storagedevice 150 may be cached in cache 216 at the server 140.

The application 210 may make requests to access one or more virtual USBmass storage devices 150. These requests are translated as transactionrequests or URBs directed to the virtual USB mass storage device 150 atthe server 140. The virtual USB bus driver 214 redirects the URBs to theclient 120 where the associated USB mass storage device 130 is located.These requests from the server 140 are transmitted to the USB massstorage device 130 via a proxy client 206. The proxy client 206transmits the requests to a stub driver 204 which transmits the requeststo the USB mass storage device 130 via USB bus driver 202. The responsesfrom the USB mass storage device 130 are transmitted back to the server140 via agent 208 and pumped to the virtual USB bus driver 214. Thevirtual USB bus driver 214 passes the responses back to the respectiveapplications 210 via the real driver 212. Application 210 may be one ormore applications and may be one or more virtual applications.

FIG. 3 is a flow chart in accordance with an embodiment of the presentdisclosure, shown generally at 300, relating to collecting metadataassociated with a USB mass storage device 130 at client 120 that is tobe redirected to a server 140. At step 302, the client 120, via proxyclient 206, polls to determine if a USB mass storage device 130 has beenconnected to client 120. Proxy client 206 may determine if a USB massstorage device 130 is connected by any process known to one of ordinaryskill in the art. For example, in one embodiment a user may use agraphical user interface (GUI) to inform the client 120 that a USB massstorage device 130 has been connected. In another embodiment, the client120 may automatically detect without user intervention the connection ofa USB mass storage device 130. USB mass storage device 130 may be anyknown mass storage device including, but not limited to, a USB thumbdrive, a USB HDD or any other USB storage device known to one ofordinary skill in the art that can be coupled to the client 120 via aUSB. Client 120 may poll for a connection in any way known to one ofordinary skill in the art, including, but not limited, waiting on aninterrupt, timer, semaphore, etc. that indicates connection of a USBmass storage device such as USB mass storage device 130.

If a USB mass storage device 130 is connected to the client 120, then atstep 304, the OS of the client 120 loads a USB bus driver 202. At step306, the proxy client 206 collects the metadata, if any, associated withthe USB mass storage device 130. For example, in one embodiment, oncethe USB mass storage device 130 is connected to the client 120, theproxy client 206 checks to see if a file system associated with the USBmass storage device 130 is mounted and if so the proxy client 206collects the metadata and stores the metadata internally.

At step 308, the client 120 notifies the server 150 that USB massstorage device 130 is connected to client 120. In one embodiment, theUSB mass storage device 130 of client 120 sends a request via proxyclient 206 to the server 140 via agent 208 to request that the server140 create a virtual USB mass storage device 150 corresponding to theUSB mass storage device 130. In another embodiment, the server 140receives a device plug-in notification from the client 120 that USB massstorage device has been connected (for example, directly orcommunicatively) to client 120. The server 140 may then determine if oneor more applications 210 need access to the USB mass storage device 130and if so the server 140 creates a virtual USB mass storage devicecorresponding to the USB mass storage device 130. In another embodiment,the server 140 automatically virtualizes the USB mass storage device 130any time the server 130 receives a notification from a client 120 that aUSB mass storage device 130 has been connected. In other embodiments,the server may only automatically redirect the USB mass storage device130 upon notification if the USB mass storage device 130 is determinedto be of a predetermined type based on one or more of the one or moreparameters received along with the device plug-in notification. Forexample, the type may be a USB thumb drive, USB HDD, or any other typeof USB mass storage device known to one of ordinary skill in the art.The predetermined type may be stored as a setting in memory, set via aGUI, or any other way known to one of ordinary skill in the art. Inanother embodiment, the server 140 may only redirect the USB massstorage device 130 when requested by an application 210. Redirection ofUSB mass storage device 130 may further be redirected according to anyother ways, processes or methods known to one of ordinary skill in theart.

At step 310, the collected metadata and one or more parametersassociated with USB mass storage device 130 are transmitted from theclient 120 via proxy client 206 to the server via agent 208. In oneembodiment, the metadata and one or more parameters may be transmittedwith the device plug-in notification sent at step 308. The one or moreparameters may include sector size, disk size, device type, serialnumber, vendor identification, manufacturer identification, productidentification or any other parameter known to one of ordinary skill inthe art.

FIG. 4 is a flow chart in accordance with one embodiment of the presentinvention shown generally at 400. At step 402, the server 140 receives anotification (for example, a device plug-in notification) from theclient 120 that a USB mass storage device 130 is ready forvirtualization such that it can be accessed from one or moreapplications 210. The notification is sent from the proxy client 206 tothe agent 208. The metadata and one or more parameters associated withthe USB mass storage device 130 are received with the device plug-innotification. At step 404, the agent 208 issues a command, for example,an I/O control (IOCTL) command or any other such command known to one ofordinary skill in the art for the virtual USB bus driver 214 to createthe virtual USB mass storage device 150. The virtual USB mass storagedevice 150 is created based, at least in part, on the notification, forexample, based on the metadata, the one or more parameters or anycombination thereof. The virtual USB bus driver 214 calls the realdriver 212 to complete the initialization of the virtual USB massstorage device 150 and based on the USB mass storage device typeenumerated by the virtual USB bus driver 214, the appropriate driverstack 218 will be created to properly manage the functionality of thevirtual USB mass storage device 150. At step 406 the driver stack 218 iscreated by the virtual USB bus driver 214.

At step 408, the server 140 retrieves from the agent 208 the completemetadata associated with the USB mass storage device 130 that has beenredirected as virtual USB mass storage device 150. At step 410, agent208 of the server 140 builds a metadata cache 216 associated with thevirtual USB mass storage device 150 to store the received completemetadata cache 216.

FIG. 5 is a flowchart in accordance with one embodiment of the presentinvention shown generally at 500. At step 502, the agent 208 receives arequest from an application 210 to access the virtual USB mass storagedevice 150. The request may be any type of I/O transaction, for examplea URB. At step 504, it is determined by the agent 208 the type ofrequest received, for example, if the request is a read request ofmetadata. If it is not a read request of metadata, then at step 508 therequest is forwarded via agent 208 to the USB mass storage device 130via proxy client 206. If it is a read request of the metadata then atstep 506, the agent 208 retrieves from the cache 216 the metadataassociated with the received request (the metadata associated with thevirtual USB mass storage device 150). The agent 208 returns a responsebased, at least in part, on the retrieved metadata to the virtual USBbus driver 214 which transmits the response back to the requestingapplication 210.

Particular embodiments may be implemented on one or more electronicdevices or information handling systems. FIG. 6 illustrates an exampleinformation handling system, computer system 600. For example, computersystem 600 may be an embodiment for a device that runs a user interfacecontent editor. In particular embodiments, one or more computer systems600 perform one or more steps of one or more methods described orillustrated herein. In particular embodiments, one or more computersystems 600 provide functionality described or illustrated herein. Inparticular embodiments, software running on one or more computer systems600 performs one or more steps of one or more methods described orillustrated herein or provides functionality described or illustratedherein. Particular embodiments include one or more portions of one ormore computer systems 600.

This disclosure contemplates any suitable number of computer systems600. This disclosure contemplates computer system 600 taking anysuitable physical form. As example and not by way of limitation,computer system 600 may be an embedded computer system, a system-on-chip(SOC), a single-board computer system (SBC) (such as, for example, acomputer-on-module (COM) or system-on-module (SOM)), a desktop computersystem, a laptop or notebook computer system, an interactive kiosk, amainframe, a mesh of computer systems, a mobile telephone, a personaldigital assistant (PDA), a server, or a combination of two or more ofthese. Where appropriate, computer system 600 may include one or morecomputer systems 600; be unitary or distributed; span multiplelocations; span multiple machines; or reside in a cloud, which mayinclude one or more cloud components in one or more networks. Whereappropriate, one or more computer systems 600 may perform withoutsubstantial spatial or temporal limitation one or more steps of one ormore methods described or illustrated herein. As an example and not byway of limitation, one or more computer systems 600 may perform in realtime or in batch mode one or more steps of one or more methods describedor illustrated herein. One or more computer systems 600 may perform atdifferent times or at different locations one or more steps of one ormore methods described or illustrated herein, where appropriate.

In particular embodiments, computer system 600 includes a processor 602,memory 604, storage 606, an I/O interface 608, a communication interface610, and a bus 612. Although this disclosure describes and illustrates aparticular computer system having a particular number of particularcomponents in a particular arrangement, this disclosure contemplates anysuitable computer system having any suitable number of any suitablecomponents in any suitable arrangement.

In particular embodiments, processor 602 includes hardware for executinginstructions, such as those making up a computer program. Theinstructions may be part of one or more modules. As an example and notby way of limitation, to execute instructions, processor 602 mayretrieve (or fetch) the instructions from an internal register, aninternal cache, memory 604, or storage 606; decode and execute them; andthen write one or more results to an internal register, an internalcache, memory 604, or storage 606. In particular embodiments, processor602 may include one or more internal caches for data, instructions, oraddresses. This disclosure contemplates processor 602 including anysuitable number of any suitable internal caches, where appropriate. Asan example and not by way of limitation, processor 602 may include oneor more instruction caches, one or more data caches, and one or moretranslation lookaside buffers (TLBs). Instructions in the instructioncaches may be copies of instructions in memory 604 or storage 606, andthe instruction caches may speed up retrieval of those instructions byprocessor 602. Data in the data caches may be copies of data in memory604 or storage 606 for instructions executing at processor 602 tooperate on; the results of previous instructions executed at processor602 for access by subsequent instructions executing at processor 602 orfor writing to memory 604 or storage 606; or other suitable data. Thedata caches may speed up read or write operations by processor 602. TheTLBs may speed up virtual-address translation for processor 602. Inparticular embodiments, processor 602 may include one or more internalregisters for data, instructions, or addresses. This disclosurecontemplates processor 602 including any suitable number of any suitableinternal registers, where appropriate. Where appropriate, processor 602may include one or more arithmetic logic units (ALUs); be a multi-coreprocessor; or include one or more processors 602. Although thisdisclosure describes and illustrates a particular processor, thisdisclosure contemplates any suitable processor.

In particular embodiments, memory 604 includes main memory for storinginstructions for processor 602 to execute or data for processor 602 tooperate on. As an example and not by way of limitation, computer system600 may load instructions from storage 606 or another source (such as,for example, another computer system 600) to memory 604. Processor 602may then load the instructions from memory 604 to an internal registeror internal cache. To execute the instructions, processor 602 mayretrieve the instructions from the internal register or internal cacheand decode them. During or after execution of the instructions,processor 602 may write one or more results (which may be intermediateor final results) to the internal register or internal cache. Processor602 may then write one or more of those results to memory 604. Inparticular embodiments, processor 602 executes only instructions in oneor more internal registers or internal caches or in memory 604 (asopposed to storage 606 or elsewhere) and operates only on data in one ormore internal registers or internal caches or in memory 604 (as opposedto storage 606 or elsewhere). One or more memory buses (which may eachinclude an address bus and a data bus) may couple processor 602 tomemory 604. Bus 612 may include one or more memory buses, as describedbelow. In particular embodiments, one or more memory management units(MMUs) reside between processor 602 and memory 604 and facilitateaccesses to memory 604 requested by processor 602. In particularembodiments, memory 604 includes random access memory (RAM). This RAMmay be volatile memory, where appropriate. Where appropriate, this RAMmay be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, whereappropriate, this RAM may be single-ported or multi-ported RAM. Thisdisclosure contemplates any suitable RAM. Memory 604 may include one ormore memories 604, where appropriate. Although this disclosure describesand illustrates particular memory, this disclosure contemplates anysuitable memory.

In particular embodiments, storage 606 includes mass storage for data orinstructions. As an example and not by way of limitation, storage 606may include a HDD, a floppy disk drive, flash memory, an optical disc, amagneto-optical disc, magnetic tape, or a Universal Serial Bus (USB)drive or a combination of two or more of these. Storage 606 may includeremovable or non-removable (or fixed) media, where appropriate. Storage606 may be internal or external to computer system 600, whereappropriate. In particular embodiments, storage 606 is non-volatile,solid-state memory. In particular embodiments, storage 606 includesread-only memory (ROM). Where appropriate, this ROM may bemask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM),electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM),or flash memory or a combination of two or more of these. Thisdisclosure contemplates mass storage 606 taking any suitable physicalform. Storage 606 may include one or more storage control unitsfacilitating communication between processor 602 and storage 606, whereappropriate. Where appropriate, storage 606 may include one or morestorages 606. Although this disclosure describes and illustratesparticular storage, this disclosure contemplates any suitable storage.

In particular embodiments, I/O interface 608 includes hardware,software, or both providing one or more interfaces for communicationbetween computer system 600 and one or more I/O devices. Computer system600 may include one or more of these I/O devices, where appropriate. Oneor more of these I/O devices may enable communication between a personand computer system 600. As an example and not by way of limitation, anI/O device may include a keyboard, keypad, microphone, monitor, mouse,printer, scanner, speaker, still camera, stylus, tablet, touch screen,trackball, video camera, another suitable I/O device or a combination oftwo or more of these. An I/O device may include one or more sensors.This disclosure contemplates any suitable I/O devices and any suitableI/O interfaces 608 for them. Where appropriate, I/O interface 608 mayinclude one or more device or software drivers enabling processor 602 todrive one or more of these I/O devices. I/O interface 608 may includeone or more I/O interfaces 608, where appropriate. Although thisdisclosure describes and illustrates a particular I/O interface, thisdisclosure contemplates any suitable I/O interface.

In particular embodiments, communication interface 610 includeshardware, software, or both providing one or more interfaces forcommunication (such as, for example, packet-based communication) betweencomputer system 600 and one or more other computer systems 600 or one ormore networks. As an example and not by way of limitation, communicationinterface 610 may include a network interface controller (NIC) ornetwork adapter for communicating with an Ethernet or other wire-basednetwork or a wireless NIC (WNIC) or wireless adapter for communicatingwith a wireless network, such as a WI-FI network. This disclosurecontemplates any suitable network and any suitable communicationinterface 610 for it. As an example and not by way of limitation,computer system 600 may communicate with an ad hoc network, a personalarea network (PAN), a local area network (LAN), a wide area network(WAN), a metropolitan area network (MAN), or one or more portions of theInternet or a combination of two or more of these. One or more portionsof one or more of these networks may be wired or wireless. As anexample, computer system 600 may communicate with a wireless PAN (WPAN)(such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAXnetwork, a cellular telephone network (such as, for example, a GlobalSystem for Mobile Communications (GSM) network), or other suitablewireless network or a combination of two or more of these. Computersystem 600 may include any suitable communication interface 610 for anyof these networks, where appropriate. Communication interface 610 mayinclude one or more communication interfaces 610, where appropriate.Although this disclosure describes and illustrates a particularcommunication interface, this disclosure contemplates any suitablecommunication interface.

In particular embodiments, bus 612 includes hardware, software, or bothcoupling components of computer system 600 to each other. As an exampleand not by way of limitation, bus 612 may include an AcceleratedGraphics Port (AGP) or other graphics bus, an Enhanced Industry StandardArchitecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT)interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBANDinterconnect, a low-pin-count (LPC) bus, a memory bus, a Micro ChannelArchitecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, aPCI-Express (PCIe) bus, a serial advanced technology attachment (SATA)bus, a Video Electronics Standards Association local (VLB) bus, oranother suitable bus or a combination of two or more of these. Bus 612may include one or more buses 612, where appropriate. Although thisdisclosure describes and illustrates a particular bus, this disclosurecontemplates any suitable bus or interconnect.

Herein, a computer-readable non-transitory storage medium or media mayinclude one or more semiconductor-based or other integrated circuits(ICs) (such, as for example, field-programmable gate arrays (FPGAs) orapplication-specific ICs (ASICs)), HDDs, hybrid hard drives (HHDs),optical discs, optical disc drives (ODDs), magneto-optical discs,magneto-optical drives, floppy diskettes, floppy disk drives (FDDs),magnetic tapes, solid-state drives (SSDs), RAM-drives, SECURE DIGITALcards or drives, any other suitable computer-readable non-transitorystorage media, or any suitable combination of two or more of these,where appropriate. A computer-readable non-transitory storage medium maybe volatile, non-volatile, or a combination of volatile andnon-volatile, where appropriate.

Those of skill in the art would appreciate that items such as thevarious illustrative blocks, modules, elements, components, methods,operations, steps, and algorithms described herein may be implemented ashardware, computer software, or a combination of both.

To illustrate the interchangeability of hardware and software, itemssuch as the various illustrative blocks, modules, elements, components,methods, operations, steps, and algorithms have been described generallyin terms of their functionality. Whether such functionality isimplemented as hardware or software depends upon the particularapplication and design constraints imposed on the overall system.Skilled artisans may implement the described functionality in varyingways for each particular application.

In one aspect, “means,” a block, a module, an element, a component or aprocessor may be an item (for example, one or more of blocks, modules,elements, components or processors) for performing one or more functionsor operations. In one aspect, such an item may be an apparatus,hardware, or a portion thereof. In one example, an item may have astructure in the form of, for example, an instruction(s) encoded orstored on a machine-readable medium, on another device, or on a portionthereof. An instruction(s) may be software, an application(s), asubroutine(s), or a portion thereof. The instructions(s) may be forperforming the function(s) or operation(s). The instruction(s) may beexecutable by one or more processors to perform the function(s) oroperation(s). One or more processors may execute the instruction(s) by,for example, transferring or copying and instructions into an executablememory space and executing the instructions. In one example, an item maybe implemented as one or more circuits configured to perform thefunction(s) or operation(s). A circuit may include one or more circuitsand/or logic. A circuit may be analog and/or digital. A circuit may beelectrical and/or optical. A circuit may include transistors. In anexample, one or more items may be implemented as a processing system(for example, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA),etc.), as a portion(s) of any of the foregoing, or as a combination(s)of any of the foregoing. Those skilled in the art will recognize how toimplement the instructions, circuits, and processing systems.

In one aspect of the disclosure, when actions or functions (for example,hooking, modifying, intercepting, redirecting, determining, traversing,obtaining, creating, operating, deleting, removing, receiving,providing, generating, converting, displaying, notifying, accepting,selecting, controlling, transmitting, reporting, sending, or any otheraction or function) are described as being performed by an item (forexample, one or more of blocks, modules, elements, components orprocessors), it is understood that such actions or functions may beperformed, for example, by the item directly. In another example, whenan item is described as performing an action, the item may be understoodto perform the action indirectly, for example, by facilitating such anaction (for example, assisting, allowing, enabling, causing, orproviding for, such action to occur; or performing a portion of such anaction). For example, determining can refer to facilitatingdetermination, attaching can refer to facilitating attaching, andreceiving can refer to facilitating receiving. In one aspect, performingan action may refer to performing a portion of the action (for example,performing a beginning part of the action, performing an end part of theaction, or performing a middle portion of the action).

A reference to an element in the singular is not intended to mean “oneand only one” unless specifically so stated, but rather “one or more.”For example, a client may refer to one or more clients, a server mayrefer to one or more servers, an operation may refer to one or moreoperations, and a signal, message, or communication may refer to one ormore signals, messages, or communications.

Unless specifically stated otherwise, the term “some” refers to one ormore. Pronouns in the masculine (for example, his) include the feminineand neuter gender (for example, her and its) and vice versa. Headingsand subheadings, if any, are used for convenience only and do not limitthe invention.

A phrase such as an “embodiment” does not imply that such embodiment isessential to the subject technology or that such embodiment applies toall configurations of the subject technology. A disclosure relating toan embodiment may apply to all embodiments, or one or more embodiments.An embodiment may provide one or more examples. A phrase such anembodiment may refer to one or more embodiments and vice versa. A phrasesuch as a “configuration” does not imply that such configuration isessential to the subject technology or that such configuration appliesto all configurations of the subject technology. A disclosure relatingto a configuration may apply to all configurations, or one or moreconfigurations. A configuration may provide one or more examples. Aphrase such a configuration may refer to one or more configurations andvice versa.

In one aspect, the term “coupled” or the like may refer to beingdirectly coupled. In another aspect, the term “coupled” or the like mayrefer to being indirectly coupled or communicatively coupled.

Various items may be arranged differently (for example, arranged in adifferent order, or partitioned in a different way) all withoutdeparting from the scope of the subject technology. In one aspect of thedisclosure, the elements recited in the accompanying claims may beperformed by one or more modules or sub-modules.

It is understood that the specific order or hierarchy of steps,operations or processes disclosed is an illustration of exemplaryapproaches. Based upon design preferences, it is understood that thespecific order or hierarchy of steps, operations or processes may berearranged. Some of the steps, operations or processes may be performedsimultaneously. Some or all of the steps, operations, or processes maybe performed automatically, without the intervention of a user. Theaccompanying method claims, if any, present elements of the varioussteps, operations or processes in a sample order, and are not meant tobe limited to the specific order or hierarchy presented.

The disclosure is provided to enable any person skilled in the art topractice the various aspects described herein. The disclosure providesvarious examples of the subject technology, and the subject technologyis not limited to these examples. Various modifications to these aspectswill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other aspects.

All structural and functional equivalents to the elements of the variousaspects described throughout this disclosure that are known or latercome to be known to those of ordinary skill in the art are expresslyincorporated herein by reference and are intended to be encompassed bythe claims. Moreover, nothing disclosed herein is intended to bededicated to the public regardless of whether such disclosure isexplicitly recited in the claims. No claim element is to be construedunder the provisions of 35 U.S.C. §112, sixth paragraph, unless theelement is expressly recited using the phrase “means for” or, in thecase of a method claim, the element is recited using the phrase “stepfor.” Furthermore, to the extent that the term “include,” “have,” or thelike is used, such term is intended to be inclusive in a manner similarto the term “comprise” as “comprise” is interpreted when employed as atransitional word in a claim.

The Title, Background, Summary, Brief Description of the Drawings andAbstract of the disclosure are hereby incorporated into the disclosureand are provided as illustrative examples of the disclosure, not asrestrictive descriptions. It is submitted with the understanding thatthey will not be used to limit the scope or meaning of the claims. Inaddition, in the Detailed Description, it can be seen that thedescription provides illustrative examples and the various features aregrouped together in various embodiments for the purpose of streamliningthe disclosure. This method of disclosure is not to be interpreted asreflecting an intention that the claimed subject matter requires morefeatures than are expressly recited in each claim. Rather, as thefollowing claims reflect, inventive subject matter lies in less than allfeatures of a single disclosed configuration or operation. The followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separately claimed subject matter.

The claims are not intended to be limited to the aspects describedherein, but are to be accorded the full scope consistent with thelanguage claims and to encompass all legal equivalents. Notwithstanding,none of the claims are intended to embrace subject matter that fails tosatisfy the requirement of 35 U.S.C. §101, 102, or 103, nor should theybe interpreted in such a way. Any unintended embracement of such subjectmatter is hereby disclaimed.

The scope of this disclosure encompasses all changes, substitutions,variations, alterations, and modifications to the example embodimentsdescribed or illustrated herein that a person having ordinary skill inthe art would comprehend. The scope of this disclosure is not limited tothe example embodiments described or illustrated herein. Moreover,although this disclosure describes and illustrates respectiveembodiments herein as including particular components, elements,feature, functions, operations, or steps, any of these embodiments mayinclude any combination or permutation of any of the components,elements, features, functions, operations, or steps described orillustrated anywhere herein that a person having ordinary skill in theart would comprehend. Furthermore, reference in the appended claims toan apparatus or system or a component of an apparatus or system beingadapted to, arranged to, capable of, configured to, enabled to, operableto, or operative to perform a particular function encompasses thatapparatus, system, component, whether or not it or that particularfunction is activated, turned on, or unlocked, as long as thatapparatus, system, or component is so adapted, arranged, capable,configured, enabled, operable, or operative.

What is claimed is:
 1. A method comprising: receiving, at an agent of aserver, a notification that a universal serial bus (USB) mass storagedevice has been connected to a client, wherein the notificationcomprises collected metadata associated with the USB mass storagedevice; creating by a virtual USB bus driver a virtual USB mass storagedevice associated with the USB mass storage device; creating a driverstack based on a device type of the USB mass storage device enumeratedby the virtual USB bus driver; building a metadata cache at the serverwith the collected metadata; receiving a request from an application toaccess the virtual USB mass storage device; determining if the requestis a read request of metadata associated with the USB mass storagedevice; and sending to the application a response based on the cachedcollected metadata.
 2. The method of claim 1, wherein the virtual USBmass storage device is created based, at least in part on thenotification.
 3. The method of claim 1, further comprising: calling bythe USB bus driver a real driver to complete initialization of thevirtual USB mass storage device.
 4. The method of claim 1, wherein theUSB mass storage device comprises one of a USB thumb drive or a USB harddisk drive.
 5. The method of claim 1, wherein the one or more parameterscomprises at least one of a device type, a serial number, vendoridentification, and manufacturer identification.
 6. The method of claim1, wherein the request from the application is a USB request block. 7.The method of claim 1, wherein the response is sent to the applicationby a real driver, and wherein the real driver receives the response fromthe virtual USB bus driver.
 8. A system comprising: a first server; oneor more central processing units for processing information of the firstserver; a memory of the first server communicatively coupled to the oneor more central processing units; and one or more modules that compriseinstructions stored in the memory, the instructions, when executed bythe one or more processing units, operable to perform operationscomprising: receiving, at an agent of a server, a notification that auniversal serial bus (USB) mass storage device has been connected to aclient, wherein the notification comprises collected metadata associatedwith the USB mass storage device; creating by a virtual USB bus driver avirtual USB mass storage device associated with the USB mass storagedevice; creating driver stack based on a device type of the USB massstorage device enumerated by the virtual USB bus driver; building ametadata cache at the server with the collected metadata; receiving arequest from an application to access the virtual USB mass storagedevice; determining if the request is a read request of metadataassociated with the USB mass storage device; and sending to theapplication a response based on the cached collected metadata.
 9. Thesystem of claim 8, wherein the virtual USB mass storage device iscreated based, at least in part on the notification.
 10. The system ofclaim 8, wherein the instructions further operable to perform operationscomprising: calling by the USB bus driver a real driver to completeinitialization of the virtual USB mass storage device.
 11. The system ofclaim 8, wherein the USB mass storage device comprises one of a USBthumb drive or a USB hard disk drive.
 12. The system of claim 8, whereinthe one or more parameters comprises at least one of a device type, aserial number, vendor identification, and manufacturer identification.13. The system of claim 12, wherein the response is sent to theapplication by a real driver, and wherein the real driver receives theresponse from the virtual USB bus driver.
 14. The system of claim 8,wherein the request from the application is a USB request block.
 15. Oneor more computer-readable non-transitory storage media embodyingsoftware operable when executed by one or more computer systems to:receive, at an agent of a server, a notification that a universal serialbus (USB) mass storage device has been connected to a client, whereinthe notification comprises collected metadata associated with the USBmass storage device; create by a virtual USB bus driver a virtual USBmass storage device associated with the USB mass storage device; createa driver stack based on a device type of the USB mass storage deviceenumerated by the virtual USB bus driver; build a metadata cache at theserver with the collected metadata; receive a request from anapplication to access the virtual USB mass storage device; determine ifthe request is a read request of metadata associated with the USB massstorage device; and send to the application a response based on thecached collected metadata.
 16. The media of claim 15, wherein thevirtual USB mass storage device is created based, at least in part onthe notification.
 17. The media of claim 15, wherein the software isfurther operable when executed to: call by the USB bus driver a realdriver to complete initialization of the virtual USB mass storagedevice.
 18. The media of claim 15, wherein the USB mass storage devicecomprises one of a USB thumb drive or a USB hard disk drive.
 19. Themedia of claim 15, wherein the one or more parameters comprises at leastone of a device type, a serial number, vendor identification, andmanufacturer identification.
 20. The media of claim 15, wherein theresponse is sent to the application by a real driver, and wherein thereal driver receives the response from the virtual USB bus driver.